EA NOT Tremolo..

[antonis]

meaning that everything seems to work O.K. but there isn't any tremolo effect ...

Some backup history:

I've build the 5th (or 6th..?) EA tremolo (RoG mod) on a well verified vero (tagboardeffects) with PS input filter cap (but NOT with reverse polarity protection.. )
Due to my fault, there was a mistake in items population - input cap (100nF) was shifted 1 row downwards, resulting in the following shem :

Of course, there wasn't any amplified signal to the ourput but all others subcircuits were O.K.
(Blinking LED rate according to Rate pot position and Depth assumed ( ) to be O.K. - I supposed that there wasn't any visual or auditory way for this kind of verification..)
I also suspect reverse polarity powering but the "guilty" person doesn't confess such an action..

After Cin correct placement, the circuit came back to it's originall form:

edit: It's not shown in the sceme but there is also a 9V1 zener between Q1 Source and Gate..

Now, (1) there is a well controled output signal (boosted and Vol settled), blinking LED rate following pot's settings BUT no audible tremolo effect..!!
       (2)There is also a constant volume sound in accordance with tremolo rate setting..!!

Obviously, for the 1st case, responsible is Q2 and/or 22μF cap and/or 470nF cap but I can't assume any interaction with the 2nd case..

A downunder fellow have proposed a 10k resistor from 9V to LED cathode but my dizzy brain refuses to unerstand the reason for this...

[duck_arse]

so does the output volume level follow the .... how can it follow the rate pot setting??

is there any DC on the depth string or Q2? ground the fet end of C22 - normal boost? what if you connect the depth string top to a V/2 (let's say) DC, and work the depth pot - volume changes? next step is show photos.

I say "10k" because it is the easiest way to say it. the sandard series rate led (to my eyes) BINKS-on-BLINKS-off like squarewave. if you feed the osc by 10k alone, it gets all the volts it can have, all to itself. then you hang an extra load, I suppose it would be, being a high-efficiency led and a big current limit, start at 22k and go up. the led then winks - on - winks - off - winks - oohh, cheeky! - again, to my eyes, like it's driven by a sinewave.

[GGBB]

If reverse power did any damage, it would probably be the 22uF. You know that Q1 is okay. Q2 gets no DC, and Q3 would not get any reverse DC because of the LED. Even if they did, there's really nothing that could be damaged by reverse power except the polar caps - *I think* - so check the 22uF - that's got to be the culprit.

Perhaps the extra noise is simply supply noise that's getting through to the oscillator because reverse power fried the filter caps?

[antonis]

so does the output volume level follow the .... how can it follow the rate pot setting??

It doesn't...
The Volume pot acts "normal" - changes the volume of the output..

is there any DC on the depth string or Q2? ground the fet end of C22 - normal boost? what if you connect the depth string top to a V/2 (let's say) DC, and work the depth pot - volume changes?

Didn't get any measurements yet but I promisse that I'll do..

If reverse power did any damage, it would probably be the 22uF. You know that Q1 is okay. Q2 gets no DC, and Q3 would not get any reverse DC because of the LED. Even if they did, there's really nothing that could be damaged by reverse power except the polar caps - *I think* - so check the 22uF - that's got to be the culprit.

Perhaps the extra noise is simply supply noise that's getting through to the oscillator because reverse power fried the filter caps?

Both seem reasonable to me...!!
(but, in case of wrong polarity, shouldn't  both Q1 & Q2 be "open" with no path to GND for the negative plate of 22μF cap ??)

[GGBB]

(but, in case of wrong polarity, shouldn't  both Q1 & Q2 be "open" with no path to GND for the negative plate of 22μF cap ??)

I'm not sure I understand that, but I think no for Q1 and yes for Q2. Q1 would still have path between power and ground via the resistors, but without the 22uF AC gain is controlled by 180R+1.2k. So it still works as a boost. Q2 can't affect the AC gain of Q1 without the 22uF. That is my suspicion as to why you have no tremolo effect.

[antonis]

Q2 can't affect the AC gain of Q1 without the 22uF. That is my suspicion as to why you have no tremolo effect.

Your suspicion have proved valid..!!!


P.S.
2nd wrong cap placement in a simple Veroboard rings the bell for an Ophthalmologist go round..